Disease or undesirable condition may occur in a human subject from any one or more of a long list of causes, including microbial infection, exposure to toxins, prolonged exposure to stress, and a diet that is either deficient in one or more essential substances, contains an excess of harmful substances, such as salt, fats, cholesterol, etc., or is otherwise unbalanced. Alternatively, or in addition, the onset and development of disease or undesirable condition may have a genetic component. In some cases, such as in cystic fibrosis or phenylketonuria, a genetic lesion is present at birth. In others, one or more genetic lesions, such as those resulting from exposure to various environmental toxins, may accumulate during a person's lifetime, eventually leading to diseases such as cancer.
Recent advances in molecular genetics have permitted large-scale sequencing of the human genome, and the creation of detailed genetic linkage maps. Such sequence and position information enable identification of chromosomal regions and specific gene sequences that are associated with a disease. Comparison of expression levels of these genes in normal and patient cells reveals that some of them are overexpresed, while others are underexpressed. It is apparent that development of a disease is often associated with a progressive, characteristic change in the pattern of gene expression. By studying the expression and function of these genes, molecular mechanisms that underlie the development and onset of many diseases are being elucidated. As a result, there is an accumulation of information connecting the risk or progress of a particular disease with the expression of specific gene sequences. Such information is being applied aggressively to develop new drugs, vaccines and therapeutic methods, such as gene therapy.
It is generally accepted that a diet consisting of an adequate number of calories and having sufficient levels of vitamins and minerals allows for proper function of the various systems, and is required to maintain a state of good health. In addition, it is well-established that many diseases and undesirable conditions can be prevented, slowed, or even reversed by modifying the subject's dietary intake. For example, deficiency diseases can generally be treated by supplementing the diet with the appropriate vitamin or mineral of which the subject is deficient. High blood pressure may be treated by restricting the subject's intake of sodium. Cardiovascular disease may be prevented, or its progression slowed or even reversed, by reducing dietary consumption of fats and cholesterol. In addition, a diet high in fruits and vegetables may reduce the risk of various types of cancer (Huang et al., in Food Phytochemicals for Cancer Prevention, Vol. 1, American Chemical Society, Washington, D.C. 1994, Chapter 1; Ho et al., in Food Phytochemicals for Cancer Prevention, Vol. 2, Chapter 1). See, for example, Wattenberg, (1993) in: Waldron et al. (eds.), Food and Cancer Prevention: Chemical and Biological Aspects, Royal Soc. Chem. pp. 12-23, which describes the presence in foods of blocking agents, i.e., agents that can prevent "genotoxic" compounds from reaching or reacting with critical target sites; and suppressing agents, i.e., agents that prevent the evolution of the neoplastic process in cells previously exposed to carcinogenic agents that would otherwise cause cancer. A general source of information regarding the effects of nutrition on gene expression can be found in Berdanier and Hargrove (eds.) (1993), Nutrition and Gene Expression, CRC Press, Boca Raton, Chapters 3, 4, 6, 8 and 11.
The role of diet in maintaining optimal health in a subject, and even in slowing or reversing the progression of disease or undesirable condition, has been the subject of much public attention, debate and commercial enterprise. For example, relatively little is known about the biological effects of phytochemicals, but it is widely believed that this group of compounds will assume a position like the vitamins in the future. (Kevin K, "Phascinating Phytochemicals: Foods of Tomorrow", Food Processing 1995, pages 79-81; Best, D. "Nutraceuticals Suit up to Play", Prepared Foods, January 1996, Pages 33-35; Weihmuller F., "Seasonings & Herbs: From Folklore to Flavors", Prepared Foods, March 1996, pages 42-54.) As for the consumers, supermarkets and health food stores provide many types of "organically grown" foods, as well as an ever-widening selection of vitamins, minerals, organic extracts and other supplements, many of which are touted as cures or preventatives for a wide range of ailments. However, for many of these foods or food supplements, there is little scientific basis underlying the claim that they are beneficial to health. Where data is available, it is usually derived from long-term epidemiological studies of humans, or studies in animals with defined diets.
Although the healthful effects of certain foods are known, the mechanism of their beneficial actions in disease prevention or treatment, especially at the gene level, is still poorly understood. No method is presently available to facilitate the systematic identification of foods or food substances capable of modulating expression of specific genes. Thus, in view of the numerous advances in the understanding of disease mechanisms and genomics, there is an increasing need for innovative methods that can rapidly and directly identify foods or food substances that have genuine healthful benefits. Having ascertained the effect certain foods or food substances have on gene expression, novel foods that can prevent or treat specific diseases can then be developed.